'The Night Fire' builds slowly with many moving pieces and loose ends. Often Harry and his unofficial partner, Renee Ballard, pull those loose ends a bit outside the bounds of legality. Harry and Ballard work well together because, while it appears they plod along in their cases, they are both thinkers. Renee tends toward the impetuous while Harry wants to play inside the lines, even though sometimes he doesn't.
I met Harry Bosch for the first time 24 years ago in 'The Black Echo'. It rather hurts to see Harry in pain both physically and as he finds his fallibility and disappointment in his mentor after death. It's sad to see Harry preparing for his own death, but he seems to be doing just that.
I think the brief encounters with both his half-brother, Mickey Haller (The Lincoln Lawyer) and his daughter Maddie are unnecessary to the main plots of 'The Night Fire' but give credence to the realization (his and ours) of his mortality.
There are no great profound messages from Michael Connelly, just great fiction born of better writing.